When it comes to commercial property insurance, one of the fundamental elements that determine your insurance rating is the construction of your building. Insurers use a system developed by the Insurance Services Office (ISO) to categorize buildings into one of six classes. These classes not only consider the materials used in construction but also the combustibility of those materials.
The Six Classes of Building Construction
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Class 1 (Frame): Buildings in this category typically have exterior walls made of wood or other combustible materials. Due to the high combustibility, these structures are considered the most likely to burn.
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Class 2 (Joisted Masonry): These buildings generally feature noncombustible exterior walls made from materials such as concrete block, stone, or brick adobe. However, they usually have combustible floors and roofs.
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Class 3 (Noncombustible): Buildings in this class have exterior walls, floors, and roofs made of noncombustible or slow-burning materials, such as metal or gypsum. Often, they are equipped with steel frames.
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Class 4 (Masonry Noncombustible): These structures often have exterior walls made of brick or concrete block, with floors and roofs constructed from metal or other noncombustible materials.
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Class 5 (Modified Fire-resistive): The walls, floors, and roofs of these buildings have a fire rating of at least two hours. They are heavily fire-resistant, typically featuring solid masonry that is at least four inches thick.
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Class 6 (Fire Resistive): Similar to Class 5, these buildings have walls, floors, and roofs with a fire rating of at least two hours. They consist of reinforced concrete that is four inches thick or more, and any structural steel used is load-bearing with a fire rating of at least two hours.
Why Building Class Matters
Underwriters take into account a number of factors when determining property insurance rates for a building. They include such things as year of construction, replacement cost valuation (RCV), and the presence (or absence) of life safety features (i.e. fire alarms, sprinkler systems, etc.). However, the most basic feature of property insurance pricing is the construction class.
Following an ISO inspection, your building will be assigned a specific class, which insurers use to assess risk and determine premiums. Buildings with higher fire resistance typically enjoy lower insurance rates due to the reduced risk of fire damage.
For more detailed information on how your building’s construction class affects your insurance rates, or to discuss your commercial property insurance needs, please reach out to our agency at 609-586-7474. Our team is here to provide you with the insights and support you need to make informed decisions about your coverage.
For more information on insuring commercial properties click here.
Image by Dmitry Spravko on Unsplash.
About the Author:
Mike Smith provides insurance brokerage and risk management guidance to apartment building owners, condo associations, and cooperatives all across the New York Metropolitan area. Drawing on over 27 years of experience in the business, as well as Rue’s extensive resources, Mike provides a thorough and consultative approach to clients’ commercial property/casualty insurance needs- with the overall aim of ensuring the broadest protection at the most competitive cost.
